Dampers and shock-absorbers are known which use a hydraulic fluid as the working medium to create damping forces to control or minimize shock and/or vibration. Typically, the damping forces are generated by pressures resisting movement between operative components of the damper or shock absorber. For example, in aircraft landing gear applications, the current state of the art is to attach a fluid damper between components of the landing gear assembly to damp shimmy motions thereof. Although these fluid devices perform acceptably, they tend to be costly and are subject to leakage thereby constituting a maintenance issue for the aircraft.
Various devices are known which utilize elastomer elements to produce a damping or locking force. In essence, the elastomer element is in friction engagement with another member and relative movement therebetween generates a quasi-frictional force or locking feature. Such devices are disclosed in U.S. Pat. No. 5,720,369 to Thorn entitled "Adjustable, Lockable Devices," U.S. Pat. No. 5,634,537 to Thorn entitled "Locking and Positioning Device," U.S. Pat. No. 5,613,580 to Young entitled "Adjustable, Lockable Strut", U.S. Pat. No. 5,535,861 to Young entitled "Dual-Rate Damper," U.S. Pat. No. 5,257,680 to Corcoran et al. entitled "Surface Effect Dampers Having Both A Hysteresis and A Frictional Component, U.S. Pat. No. 5,183,137 to Siwek et al. "Dual Rate Surface Effect Dampers" U.S. Pat. No. 4,964,516 to Thorn entitled "Damped Extended-Motion Strut," U.S. Pat. No. 4,957,279 to Thorn entitled "Fluidless Multi-Directional Motion-Damping Mount," and U.S. application Ser. No. 09/040,694 to Thorn et al. entitled "Resistance Generating Device" all of which are commonly assigned to the assignee of the present invention. Although these devices are adequate for their intended purposes, they each exhibit certain inadequacies which make them unattractive candidates for providing damping forces between relatively moveable members. In particular, many of the devices available heretofore provide damping forces that vary significantly with temperature variations.
Therefore, there is a long felt, and urgent, need for a simple, durable, maintenance free and cost effective device for providing damping forces between relatively moveable members, and in particular, a damper which is substantially temperature insensitive.